Molten salt nuclear reactor that eats radioactive waste gets funded

Nuclear power was the resurgent darling of the energy industry just a few years ago as concerns over global warming mounted. Then there was the disastrous meltdown of the Fukushima Daiichi plant in central Japan, which will continue to affect residents for years to come. In the wake of this event, nuclear plants in Japan and Germany were completely shut off and plans to expand nuclear power around the world were shelved.

A few companies have continued pushing safer forms of nuclear power in a smaller form, and now one of them is getting the finding to make its plans a reality. Transatomic Power has just picked up $2 million from Founders Fund to develop a custom molten salt reactor that can eat nuclear waste.

Transatomic is an MIT spin-off founded by Leslie Dewan and Mark Massie that aims to make nuclear power more efficient by focusing on smaller, high-efficiency plants that can be built in a factory and shipped by train to their destination. It’s not just the size that’s getting investors all hot and bothered. Transatomic has designed a system that can use different types of fuel, including materials that are discarded as waste from traditional nuclear plants. We might as well eke a little more power out of it instead of sealing it up in metal caskets for 100,000 years, right?

Molten salt reactor designs are appealing because they are essentially immune to meltdowns like the one we saw at Fukushima. A standard nuclear plant is cooled by water, which boils well below the 2,000 degrees Celsius at the core of a nuclear fuel pellet. The fission happening in these reactors is a chain reaction, meaning it keeps going until we stop it, or it runs out of fuel. Shutting down one of these reactors means pumping in water until it has cooled, which can take a long time. If that doesn’t happen — because maybe you had to run away from radiation — the reaction continues out of control and you can get a meltdown.

Reactors like the one proposed by Transatomic use salt mixed with the nuclear fuel to slow the reaction. When the temperature goes up, the salt expands and reduces the rate of fission. Since salt’s melting point is higher than the core temperature, even if power is lost and no one is around to fix things, the reaction will eventually stop on its own. This technology has been proposed before, but Transatomic says it can do it better withimproved internal reactor geometry (PDF). This is what could allow it to fuel a reactor with nuclear waste or mined uranium at enrichment levels as low as 1.8 percent.

Transatomic’s designs are also interesting because they cannot be used to produce weapons-grade radioactive materials. At the same time, it pumps out 500 megawatts of juice — that’s still only half of a standard plant, but this one would be much smaller and produces only a fraction of the high-level waste products. The new round of funding should get Transatomic to the point of validating its reactor design. The next step is to build finished versions of the plant – the first unit is expected to cost $1.7 billion, though. Commercial production could begin as soon as 2020, and by then maybe you won’t mind having a nuclear power plant in your backyard.